Ubuntu on an old Pentium (GRUB needs uppermem)

[Wim Wolters]

Hi Marius,
Thank you very much for your explanation. I'll see what I can do with it. You never can tell.
William	


> Van: Marius Gedminas <marius at pov.lt>
> Aan: ubuntu-users at lists.ubuntu.com
> Subject: Ubuntu on an old Pentium (GRUB needs uppermem)
> BCC: Thu, 12 Jan 2006 13:26:40 +0200

> Hi,
>   Summary: Breezy doesn't boot on an old Packard Bell machine out of the
>   box.  It is possible to make it boot by changing GRUB's menu.lst, but
>   a kernel upgrade will regenerate that file and wipe out the workaround.
> We've had an old Pentium machine (120 Mz, 64 MB RAM) used as a
> router/firewall at our office.  It ran a floppy distro (LEAF Bering).
> Any change to the firewall configuration required a trip to the server
> room because SSH didn't fit on the floppy.
> Recently my coworker Albertas found a small spare hard disk and tried to
> install Ubuntu on the machine.  It turned out to be a painful procedure.
> GRUB would load the kernel, and the kernel would then fail to recognize
> initrd.img (RAMDISK: couldn't find valid ram disk image at offset 0),
> and without initrd.img it wouldn't have any IDE drivers for accessing
> the disk.
> Albertas then noticed some discrepancies in reported memory size.  The
> BIOS said there were 64 megs.  Memtest said there were 55 megs (plus 8
> megs that were "reserved"; I've no idea for what).  GRUB said there were
> only 8 megs (!).
> The solution turned out to tell GRUB that there are 55 megs of upper
> memory, and tell the kernel there are 56 megs total.  Albertas did that
> from the GRUB command line, booted, and made the necessary modifications
> to /boot/grub/menu.lst.  The modifications are as follows:
>   1. Edit menu.lst and add 'mem=56M' to the '# kopt=...' line.
>   2. Run update-grub to make the mem= option propagate to the automatic
>      kernels list
>   3. Edit menu.lst and add
>         uppermem 56320
>      before each 'kernel' line (except for the memtest entry).
> You have to manually repeat step 3 every time you run update-grub (which
> means after every kernel upgrade).  It would be easy to forget.  Is
> there any way to avoid the need for continued manual menu.lst
> modifications?
> By the way, the kernel also reports that 16 megs out of those 56 are
> "reserved", and only gets 40 usable megs (45 after the initial ramdisk
> is freed).  I have no idea why 30% of RAM gets reserved.
> A few years ago I ran Debian on that machine.  I do not remember ever
> having to manually specify memory size anywhere to get it to boot.
> It is possible, that it is a GRUB problem, and you don't actually have
> to tell the kernel anything.  I used LILO in Debian.  It is also
> entirely possible that I had compiled a custom kernel and did not use an
> initrd.  I do not rememeber.
> Marius Gedminas
> -- 
> To err is human, but to really foul things up requires a computer.
> </pre><pre>-- 
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